The occurrence of high nitrate levels in groundwater has to be recognized as a threat to humans and animals. Infant methaemoglobinaemia and nitrate poisoning in livestock occur at unexpected times and places. Nitrate pollution in the groundwater is one of the major pollution problems. In the last few decades nitrate concentration in groundwater has increased dramatically. Groundwater contamination by nitrate (NO3-) is a global problem and is most often associated with leachates derived from fertilizers and animal or human wastes. The study presented here was carried out in Varanasi district. The nitrate content in water was investigated during premonsoon (March-April, 2013) and postmonsoon (November-December, 2013) seasons and compared with the standard values given by WHO. Eighty four, from different cropping systems (i.e. rice-wheat, rice-vegetable, vegetable-vegetable, pulse-pulse, orchard and sugarcane) groundwater samples were collected from the bore wells. The analysis of nitrate in these water samples reveals that some villages have a high concentration of nitrate, exceeding permissible limits of WHO (45 mg/L), which is due to the more than the required quantity of nitrogen based fertilizers, water, manure and pesticides are used extensively which all contribute to the non point source contamination of nitrates in groundwater of the study area.

Urban environmental pollution intensifies with the acceleration of industrialization and urbanization. Urban green space plays an important role in improving the quality of urban environment. Statistical reports from 2002 to 2013 were analysed to estimate the environmental purification value of urban green space in Nanjing by using the production cost method and substituted expenses method. Results showed that the environmental purification value of urban green space from 2002 to 2013 increased from 0.212 billion to 0.354 billion RMB, showing an increase of 0.142 billion RMB and an annual average growth rate of 14% in the past 12 years. Carbon fixation and oxygen release of urban green space ecosystems are transferable in regional space | hence, these services can be performed by the natural ecosystems beyond the city. However, harmful gas absorption, dust detention and noise reduction of urban green space is not transferable in space and thus must be performed by the urban ecosystem. Therefore, aside from innovating technologies for pollution-reducing and pollution-controlling, increasing green space coverage, optimizing green plant distribution structure, and enhancing urban green space management must be executed to improve the urban ecological environment.